This invention relates generally to the use of a pulsed flow of chemical etchant in chemical etching manufacturing systems to remove material from a workpiece, and to a method for use thereof.
There are a wide variety of conventional chemical etching manufacturing systems using a continuous flow of etchant to remove material from a workpiece including spray etching, immersion etching, and bubble etching. The use of a uniform flow of etchant in each of these conventional chemical etching manufacturing systems is subject to certain limitations and disadvantages.
In spray etching systems, a workpiece is horizontally or vertically positioned in a box-like chamber with spray nozzles directing a uniform flow of etchant against the workpiece. The spray nozzles are oriented to enhance coverage of etchant on the workpiece as well as to introduce fresh etchant to the workpiece coverage area. The use of a uniform flow of etchant on a horizontally or vertically positioned workpiece generally results in non-uniform etching with different areas of the workpiece receiving varying amounts of etchant, especially at the edges of the workpiece.
In immersion etching systems, a workpiece is immersed in chemical etchant until the etching is complete. Process times are generally long and known heating and mechanical agitation methods tend to lead to non-uniform etching.
Bubble etching is a modified form of immersion etching, using air bubbled through the chemical etching solution past the workpiece being etched. The bubbling of air assists in removing material and providing fresh etchant at the etched surface. However, it is often difficult to obtain a uniform distribution of bubbles throughout the workpiece and therefore difficult to obtain uniform etching.
In all of these chemical etching manufacturing systems, the use of an uniform flow of etchant on a workpiece may lead to problems with non-uniform etching and to overall difficulties with the precision of the etching.